JP2006140216A - Double-sided circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board where a minute circuit can be formed and an yield of a product is improved, and to provide a manufacturing method of the circuit board. <P>SOLUTION: The manufacturing method of the double-sided circuit board where conductor layers 2 formed on both faces of an insulating board 10 are electrically connected through a through-hole has a process for forming the conductor layers 2 on both faces of the insulating board 10, a process for forming a first mask 31 on the surface of a first conductor layer 21, a process for forming the through-hole 53 penetrating the circuit board, a process for forming a second mask 32 on the surface of a second conductor layer 22, a process for forming first through-hole plating 41 in the through-hole 53 by applying a current to the first conductor layer 21 and forming second through-hole plating 42 in the through-hole 53 by applying a current to the second conductor layer 22, and a process for removing the first mask 31 and the second mask 32. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a double-sided circuit board and a manufacturing method thereof. In particular, the present invention relates to a double-sided circuit board having a through hole and a method for manufacturing the double-sided circuit board.

  In recent years, with the miniaturization of electronic devices, circuit boards mounted therein are required to be three-dimensional, thin, multilayered, and fine. To meet these requirements, a flexible substrate using a thin and soft flexible material as an insulating material is suitable, and the demand for this flexible substrate is rapidly increasing. However, with respect to multilayering and miniaturization of circuit boards, sufficient technology has not been established, and there is an urgent need to establish a through-hole connection structure and a manufacturing method that are one of these factors.

  The above through-hole connection means that a hole (hereinafter referred to as a through-hole hole) is passed through a double-sided circuit board in which a conductor layer is formed on both sides of an insulating substrate, and a metal plating layer is formed in the through-hole hole. FIG. 10 shows a conventional double-sided circuit board using the through-hole connection.

  In such a conventional double-sided circuit board manufacturing process, when the electrolytic metal plating layer 43 is formed in the through hole 53, the electrolytic metal plating layer 43 is also formed on the surface of the conductor layer 2 at the same time. The electrolytic metal plating layer 43 in the through-hole hole 53 needs to be thick in order to ensure connection reliability. Therefore, the electrolytic metal plating layer 43 is formed thick on the surface of the conductor layer 2. The laminated body 44 of the conductor layer 2 and the electrolytic metal plating layer 43 was thick. For this reason, when a conductor pattern is formed from this laminated body 44 by the subsequent etching process, the direction of etching is directed not only in the plate thickness direction but also in the plane direction. As a result, the line width and the line interval of the conductor pattern have to be increased, and a fine circuit cannot be formed.

  In addition, even when a flexible circuit board is used as the insulating substrate 10 to produce a circuit board that can be bent, the flexibility of the circuit board has been impaired due to the thickness of the laminated body 44 described above.

Therefore, in Patent Document 1, the above problem is solved by forming the electrolytic metal plating layer 43 only around the through-hole hole 53 as shown in FIG.
Japanese Patent No. 3048360

  However, the technique disclosed in Patent Document 1 has the following problems.

  In the technique disclosed in Patent Document 1, since the conductor layer 2 is etched before electrolytic metal plating, the conductor layer 2 for connecting the through hole is formed around the through hole hole 53 during the etching process. Lands 52 (hereinafter referred to as through-hole lands) are formed. In the subsequent electrolytic metal plating process, the surface of the conductor layer 2 is masked except for the through-hole holes 53 and the through-hole lands 52 so that the electrolytic metal-plated layer 43 does not adhere to other than the through-hole holes 53 and the through-hole lands 52. do. However, this masking operation becomes difficult when the diameter of the through-hole land 52 is small. Therefore, it is necessary to increase the diameter of the through-hole land 52 in advance. It becomes an obstacle.

  Further, as shown in FIG. 11, in the through hole land 52 portion, the laminated form of the conductor layer 2 and the electrolytic metal plating layer 43 on the insulating substrate 10 is stepped. In general, since the insulating substrate 10 has a higher coefficient of thermal expansion than the conductor layer 2 and the electrolytic metal plating layer 43, if the laminated form of the conductor layer 2 and the electrolytic metal plating layer 43 is stepped, the manufacturing process of the double-sided circuit board In this case, there is a possibility that the through-hole connection is broken due to the thermal cycle applied to the insulating substrate 10.

  Further, if the laminated form of the conductor layer 2 and the electrolytic metal plating layer 43 is stepped, this portion will protrude greatly from the double-sided circuit board surface. When a protective film is coated on a double-sided circuit board having such a large protruding part or a multilayer circuit board is produced using this double-sided circuit board, a void may be formed around the protruding part. This caused the peeling of the protective film and the peeling of the multilayer circuit board.

  In addition, since the surface of the double-sided circuit board has large irregularities, it is difficult to connect the part to the circuit of the board or to fix the part to the board when mounting the part on the surface of the board. There is a problem.

  Furthermore, as shown in FIG. 11, since the electrolytic metal plating layer 43 is not filled up to the center of the through-hole hole 53 even after the electrolytic metal plating process, the double-sided circuit board is covered with a protective film, When a multilayer circuit board is manufactured using this double-sided circuit board, a closed space is formed in the through-hole hole 53. If heat is applied to the circuit board in such a state, the air in the center of the through-hole hole 53 may thermally expand, and the through-hole connection may be disconnected.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a double-sided circuit board capable of forming a fine circuit and improving the product yield and a method for manufacturing the same.

  In order to solve the above problems, a method for manufacturing a double-sided circuit board according to the present invention is the method for manufacturing a double-sided circuit board in which conductor layers provided on both sides of an insulating substrate are electrically connected through a through hole. A step of forming conductor layers on both sides of the substrate, and using either one of the conductor layers as a first conductor layer and the other as a second conductor layer, a first mask on the surface of the first conductor layer; Forming a through-hole hole penetrating through the first mask, the first conductor layer, the insulating substrate, and the second conductor layer, and the second of the through-hole hole. Forming a second mask on the surface of the second conductor layer so as to close the opening on the conductor layer side of the first conductor layer, and passing through the first conductor layer to energize the first in the through-hole hole. Through-hole plating And a step of forming a second through-hole plating in the through-hole hole by energizing the second conductor layer, and a step of removing the first mask and the second mask. It is characterized by.

  According to such a manufacturing method of the present invention, since the first and second through-hole platings are formed only in the through-hole holes, the masking operation for aligning the opening of the mask with the through-hole lands. Is not necessary. For this reason, not only the masking work of the first and second masks is easy, but also the through-hole land diameter can be reduced, and a fine circuit can be manufactured. In the through-hole land portion, the conductor layer and the electrolytic metal plating layer are not formed stepwise on the insulating substrate, and the through-hole connection is less likely to be disconnected due to the thermal cycle applied to the insulating substrate. Further, the first mask at a position corresponding to the opening on the first conductor layer side of the through hole is a through hole penetrating the first mask, the first conductor layer, the insulating substrate, and the second conductor layer. Since it is removed by forming the hole hole, the position and shape of both of the through hole hole and the opening of the first mask corresponding to the opening are accurately determined. Can be matched.

  Also, the method for manufacturing a double-sided circuit board according to the present invention is a method for manufacturing a double-sided circuit board in which conductor layers provided on both sides of an insulating board are electrically connected through a through hole. The step of forming a conductor layer, and one of these conductor layers as a first conductor layer and the other as a second conductor layer, the first conductor layer, the insulating substrate, and the second conductor layer Forming a through hole hole penetrating through the first conductor layer and forming a first mask on the surface of the first conductor layer so as to close the opening of the through hole hole on the first conductor layer side. And removing the first mask at a location corresponding to the opening, and the surface of the second conductor layer so as to close the opening on the second conductor layer side of the through hole. Forming a second mask on the substrate; and Forming a first through-hole plating in the through-hole hole by energizing the conductor layer, and forming a second through-hole plating in the through-hole hole by energizing the second conductor layer. And a step of removing the first mask and the second mask.

  According to such a manufacturing method of the present invention, since the first and second through-hole platings are formed only in the through-hole holes, the masking operation for aligning the opening of the mask with the through-hole lands. Is not necessary. For this reason, not only the masking work of the first and second masks is easy, but also the through-hole land diameter can be reduced, and a fine circuit can be manufactured. In the through-hole land portion, the conductor layer and the electrolytic metal plating layer are not formed stepwise on the insulating substrate, and the through-hole connection is less likely to be disconnected due to the thermal cycle applied to the insulating substrate. Further, the first mask corresponds to the opening after forming the first mask on the surface of the first conductor layer so as to close the opening on the first conductor layer side of the through hole. Since the first mask is removed, the position and shape of the through hole hole and the opening portion of the first mask corresponding to the opening portion exactly match each other. Can be made.

  Here, a resin film may be used for the first mask.

  In this case, since a resin film is used for the first mask, it is easy to stack the first mask on the surface of the first conductor layer, and the first step is a step of forming a through-hole hole. It is also easy to process the opening of the mask.

  Further, a resin film is used for the first mask, and the removal of the first mask at a position corresponding to the opening of the through-hole hole is performed by opening the through-hole hole on the second conductor layer side. May be performed by irradiating with laser light.

  In this case, a resin film is used for the first mask, and the removal of the first mask at a position corresponding to the opening of the through hole hole is performed by applying laser light from the opening of the through hole hole on the second conductor layer side. Since it is performed by irradiating, the position and shape of both of the through-hole hole and the opening of the first mask corresponding to the opening can be accurately matched.

  Further, a photosensitive resin is used for the first mask, and the removal of the first mask at a position corresponding to the opening of the through-hole hole is performed by opening the through-hole hole on the second conductor layer side. You may perform by exposing from a part.

  In this case, a photosensitive resin is used for the first mask, and the removal of the first mask at a position corresponding to the opening of the through hole is exposed from the opening of the through hole on the second conductor layer side. Therefore, the position and shape of the through-hole hole and the opening of the first mask corresponding to the opening can be accurately matched.

  Further, the second mask may be provided on the second conductor layer through an adhesive material mixed with particles of a conductive material.

  In this case, since the second mask is provided on the second conductor layer via an adhesive material mixed with conductive material particles, the through-hole plating is not performed in the through-hole plating forming process. Growth to the center of the hole can be promoted. Thereby, the through-hole plating is uniformly formed in the through-hole hole, and the formation time of the through-hole plating is shortened.

  The conductive material particles may be non-metallic.

  In this case, since the particles of the conductive material are non-metallic, the conductive material is not easily corroded when the electrolytic plating process is performed.

  The conductive material particles may be carbon particles.

  In this case, the conductive material particles are carbon particles having excellent performance such as conductivity, thermal conductivity, acid resistance, alkali resistance, heat resistance, and the like. Is less likely to corrode and can further promote the growth of through-hole plating.

  The conductive material particles may be carbon nanotube particles.

  In this case, since the particles of the conductive material are carbon nanotube particles having performances such as conductivity and thermal conductivity that are superior to those of carbon, the conductive material is corroded during the electrolytic plating process. It is difficult to further promote the growth of through-hole plating.

  Here, the second through-hole plating may be formed before the first through-hole plating.

  In this case, since the second through-hole plating is formed before the first through-hole plating, the through-hole plating is satisfactorily filled without any gaps. For this reason, it is difficult to form a thin portion in the through-hole plating, and the through-hole connection is difficult to be disconnected.

  Further, the formation of the first and second through-hole platings may be performed using a copper-based plating material.

  In this case, since the formation of the first and second through-hole platings is performed using a copper-based plating material, the through-hole plating can be easily satisfactorily filled in the through-hole plating. Thin portions are not easily formed, and through-hole connections are difficult to break.

  A double-sided circuit board according to the present invention is manufactured by the manufacturing method described in any one of the above.

  According to such a double-sided circuit board of the present invention, the first and second through-hole platings are formed only in the through-hole holes, and the stepped shape of the conductor layer and the electrolytic metal plating layer is formed on the insulating substrate. Since a laminated form is not formed, this portion does not protrude significantly from the double-sided circuit board surface. Thus, even if this double-sided circuit board is covered with a protective film or a multilayer circuit board is produced using this double-sided circuit board, it is difficult for voids to be formed around this part. Circuit board delamination is less likely to occur.

  In addition, since a step-like layered form is not formed around the through hole, the surface of the double-sided circuit board cannot be greatly uneven. As a result, when a component is mounted on the surface of the substrate, the component can be connected to the circuit of the double-sided circuit board and the component can be fixed to the double-sided circuit board.

  Furthermore, since the inside of the through-hole is completely filled by through-hole plating during electrolytic metal plating, this double-sided circuit board is covered with a protective film, or a multilayer circuit board is produced using this double-sided circuit board. Even in this case, a closed space is not formed in the through-hole hole. Thereby, the problem of disconnection of the through-hole connection caused by thermal expansion of air in the closed space does not occur.

  The double-sided circuit board and the method for manufacturing the same according to the present invention have the effect that a fine circuit can be formed and the yield of products can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  Hereinafter, the manufacturing method of Example 1 will be described with reference to FIG.

  FIG. 1 is a cross-sectional view of a double-sided circuit board showing a manufacturing process in Example 1 of the present invention.

  First, as shown in FIG. 1A, the conductor layer 2 is formed on both surfaces of the insulating substrate 10.

  The insulating substrate 10 constitutes a base of a double-sided circuit board. As this insulating substrate 10, either a rigid substrate or a flexible substrate may be used, and the material thereof is not particularly limited. Generally, a phenol resin, a polyester resin, an epoxy resin, a polyimide resin, a fluorine resin, or the like is used. Often used are those reinforced with paper, non-woven fabric, glass fiber, aramid fiber or the like in order to improve dimensional stability and strength. The insulating substrate 10 is preferably 40 μm or less in thickness, and if the thickness is further reduced, the distance between the conductor layers 2 is shortened, and the growth distance in the thickness direction of the through-hole plating 4 can be reduced. It can be formed well.

  The conductor layer 2 is a portion to be a conductor pattern of the double-sided circuit board by finally etching the conductor layer 2. The conductor layer 2 is not particularly limited as long as it is a conductive material. In general, a copper foil having a thickness of about 18 to 35 μm is often used, and is insulated with or without an adhesive. It is laminated on the substrate 10. Also, the conductor layers 2 provided on both surfaces of the insulating substrate 10 may be made of different materials and thicknesses.

  As a specific configuration of this example, 20 μm polyimide resin was used for the insulating substrate 10, 18 μm copper foil was used for the conductor layer 2, and copper foil was laminated on both sides of the polyimide resin with an adhesive.

  Next, as shown in FIG. 1B, either one of the conductor layers 2 is a first conductor layer 21 and the other is a second conductor layer 22. A mask 31 is formed. At this time, the first mask 31 at a location corresponding to the opening of the through hole 53 on the first conductor layer 21 side is not removed.

  The first mask 31 is for preventing an electrolytic metal plating layer from being formed on the surface of the first conductor layer 21 in the steps shown in FIGS. 1 (e) and 1 (f). The first mask 31 preferably satisfies the following characteristics. First, it has heat resistance to heat generated during manufacture, good workability for opening the through-hole hole 53, and high resistance to electrolytic plating, and further, an electrolytic metal plating layer is hardly formed on the mask surface. A mask material that can be satisfactorily removed in the step shown in (g) is preferable. For example, a mask material that is applied in a liquid state and cured, and a mask material that is laminated in a film form via an adhesive material can be used. In this example, good results were obtained when a resin film that was easy to stack and had good workability was used for the first mask 31.

  The pressure-sensitive adhesive material is applied to the film-like first mask 31 so that the first mask 31 is adhered to the surface of the first conductor layer 21. The adhesive material has heat resistance to heat generated during production, good workability for opening the through-hole hole 53, and high resistance to electrolytic plating treatment, and is well removed in the process shown in FIG. 1 (g). The removal method in the step shown in FIG. 1 (g) is, for example, an adhesive material that can be easily peeled off by irradiating with ultraviolet rays or an adhesive material with low adhesive strength.

  Specifically, in this embodiment, a first mask 31 is manufactured by applying a low-adhesive adhesive material to a heat-resistant polyester having a thickness of 20 μm, which is a film-like mask material, in a thickness of 4 μm. The mask 31 was roll laminated on the surface of the first conductor layer 21.

  Next, as shown in FIG. 1C, a through-hole hole 53 penetrating the first mask 31, the first conductor layer 21, the insulating substrate 10, and the second conductor layer 22 is formed.

  The through hole 53 is a hole penetrating the double-sided circuit board, and is used for electrically connecting the first conductor layer 21 and the second conductor layer 22 through the hole 53. The method for opening the through-hole hole 53 is not particularly limited, and examples thereof include drilling and laser processing. The diameter of the through-hole hole 53 is preferably 120 μm or less, and the smaller the diameter, the shorter the growth distance in the surface direction of the through-hole plating 4 in the process shown in FIGS. 1 (e) and 1 (f). The through-hole plating 4 is formed satisfactorily. In addition, this makes it possible to reduce the size of the through hole portion, so that a fine circuit can be easily manufactured.

  Specifically, in this embodiment, the first mask 31, the first conductor layer 21, the insulating substrate 10, and the second conductor layer 22 are drilled through a hole, and a through-hole hole 53 having a diameter of 40 μm. Formed.

  Next, as shown in FIG. 1D, a second mask 32 is formed on the surface of the second conductor layer 22 so as to close the opening of the through hole 53 on the second conductor layer 22 side. To do.

  The second mask 32 is for preventing an electrolytic metal plating layer from being formed on the surface of the second conductor layer 22 in the steps shown in FIGS. 1 (e) and 1 (f). The second mask 32 preferably satisfies the following characteristics. First, a mask that is required to have heat resistance to heat generated during manufacturing and high resistance to electrolytic plating treatment, and that an electrolytic metal plating layer is not easily formed on the mask surface, and can be removed well in the process shown in FIG. Good material. For example, there is a mask material that is easy to close the opening and is laminated with an adhesive.

  The pressure-sensitive adhesive material is applied to the film-like second mask 32 to adhere the second mask 32 to the surface of the second conductor layer 22. The adhesive material is preferably an adhesive material that has heat resistance to heat generated during production and high resistance to electrolytic plating treatment, and can be removed well in the process shown in FIG. 1 (g). Examples thereof include an adhesive material that is easily peeled off and an adhesive material having a low adhesive strength. In addition, the adhesive material is preferably one in which an electrolytic metal plating layer is easily formed on the surface of the adhesive material and can assist the growth of the electrolytic metal plating layer, and examples thereof include an adhesive material mixed with particles of a conductive material. The particles of the conductive material are preferably non-metals that are not easily corroded in the electrolytic plating process, and examples thereof include carbon particles and carbon nanotube particles.

  Specifically, in this example, carbon nanotube particles are mixed into a low-adhesive adhesive material, and the adhesive material is applied to a heat-resistant polyester having a thickness of 20 μm, which is a film-like mask material, to a thickness of 4 μm. A second mask 32 was produced, and this mask 32 was roll laminated on the surface of the second conductor layer 22.

  Next, as shown in FIGS. 1E and 1F, the first conductor layer 21 is energized to form the first through-hole plating 41 in the through-hole hole 53, and the second conductor By energizing the layer 22, a second through-hole plating 42 is formed in the through-hole hole 53.

  The first through-hole plating 41 and the second through-hole plating 42 are for electrically connecting the first conductor layer 21 and the second conductor layer 22. As the plating material, a material that is conductive and easily fills into the concave through-hole hole 53 is desirable, and examples thereof include a copper-based material.

  Here, the second through-hole plating 42 and the first through-hole plating 41 may be formed first or may be formed simultaneously.

  However, when the first through-hole plating 41 is formed earlier than the second through-hole plating 42, or when these are formed simultaneously, the first through-hole plating 41 grows, and depending on the conditions, the through-hole plating is performed. The opening on the first conductor layer 21 side of the hole 53 is blocked, and the through hole plating 4 cannot be filled up to the bottom of the through hole hole 53 on the second mask 32 side. Further, even if the second conductor layer 22 is energized after that, a closed space is formed in the bottom portion of the through-hole hole 53 by the first through-hole plating 41 and the second mask 32. The formation of the second through-hole plating 42 is hindered on the way. As a result, the first conductor layer 21 and the second conductor layer 22 may not be electrically connected. Even if they are connected, the thickness of the through-hole plating 4 is reduced, There is a possibility that voids are formed in the hole plating 4 and the through-hole connection is broken. From the above, whether the first through-hole plating 41 is formed earlier than the second through-hole plating 42 or the case where they are formed simultaneously, the through on the second mask 32 side Until the through hole plating 4 is filled to the bottom of the hole hole 53, it is necessary to prevent the opening of the through hole hole 53 on the first conductor layer 21 side from being blocked.

  Next, the case where the formation of the second through-hole plating 42 is performed before the formation of the first through-hole plating 41 will be described with reference to FIG.

  3A is a cross-sectional view of the double-sided circuit board before the electrolytic plating process, and FIG. 3B is a cross-sectional view of the double-sided circuit board showing a growth state of the through-hole plating 4 formed by the electrolytic plating process. FIG. In FIG. 3B, the vertical axis represents the growth state of the second through-hole plating 42 formed earlier, and the horizontal axis represents the growth state of the first through-hole plating 41 formed thereafter.

  First, as shown in FIG. 3, by changing the electrolytic plating conditions of the second conductor layer 22, the second through-hole plating 42 is in the state 1 (the second through-hole plating 42 is in the through-hole hole 53. State 2 (the state where the second through-hole plating 42 has grown to the position of the insulating substrate 10) and state 3 (the state where the second through-hole plating 42 has reached the position of the first mask 31). A grown state). From these states, the first through-hole plating 41 is changed from the state A (the state in which only the upper peripheral edge of the first through-hole plating 41 has grown to the position of the first mask 31) to the state B (first through-hole plating). Even when the upper end of 41 is uniformly grown to a position exceeding the first conductor layer 21), no void is formed in the through-hole hole 53, and the bottom of the through-hole hole 53 is also formed. The through-hole plating 4 is satisfactorily filled.

  As described above, even when the first through-hole plating 41 is formed before the second through-hole plating 42 or when these are formed at the same time, the conditions are controlled to obtain a good through-hole plating 4. However, when the second through-hole plating 42 is formed earlier than the first through-hole plating 41, the good through-hole plating 4 can be obtained more stably.

  By the way, the second through-hole plating 42 is formed first, and the bottom of the through-hole hole 53 is filled with the second through-hole plating 42, and then the first conductor layer 21 and the second conductor layer 22 are formed. It may be energized at the same time. In that case, the formation efficiency of the through-hole plating 4 is improved, and a uniform through-hole plating 4 can be obtained.

  Next, as shown in FIG. 1G, the first mask 31 and the second mask 32 are removed.

  Finally, as shown in FIG. 1H, the surface of the first through-hole plating 41 is smoothed. An example of this method is physical polishing.

  The order of steps for removing the first mask 31 and the second mask 32 and smoothing the surface of the first through-hole plating 41 is shown in FIGS. 1 (g) and 1 (h). The first mask 31 may be removed first, and then the surface of the first through-hole plating 41 may be polished, and then the second mask 32 may be removed.

  Next, Embodiment 2 of the present invention will be described with reference to FIG.

  FIG. 2 is a cross-sectional view of a double-sided circuit board showing a manufacturing process in Example 2 of the present invention.

  In addition, since the manufacturing method of the double-sided circuit board according to this embodiment is basically the same as that of the first embodiment described above, the same members are denoted by the same reference numerals, and the description thereof is omitted. I will explain only.

  In the first embodiment, the first mask 31 is laminated on the double-sided circuit board, and then the through hole hole 53 is opened. In the second embodiment, the through hole hole 53 is opened in the double-sided circuit board. After that, the first mask 31 was laminated. Details will be described below.

  As shown in FIG. 2B, the first conductor layer 21, the insulating substrate 10, and the second conductor layer 2 are used as the first conductor layer 21 and the other as the second conductor layer 22. A through-hole hole 53 penetrating the conductor layer 22 is formed.

  The through-hole 53 is a hole that penetrates the circuit board, and is used to electrically connect the first conductor layer 21 and the second conductor layer 22 through the hole. The method for opening the through-hole hole 53 is not particularly limited, and examples thereof include drilling and laser processing. The diameter of the through-hole hole 53 is preferably 120 μm or less, and the smaller the diameter, the shorter the growth distance in the surface direction of the through-hole plating 4 in the steps shown in FIGS. 2 (e) and 2 (f). The through-hole plating 4 is formed satisfactorily. In addition, this makes it possible to reduce the size of the through hole portion, so that a fine circuit can be easily manufactured.

  As shown in FIG. 2C, after forming the first mask 31 on the surface of the first conductor layer 21 so as to close the opening of the through hole 53 on the first conductor layer 21 side. The first mask 31 corresponding to the opening is removed.

  The first mask 31 is for preventing an electrolytic metal plating layer from being formed on the surface of the first conductor layer 21 in the steps shown in FIGS. 2 (e) and 2 (f). The first mask 31 preferably satisfies the following characteristics. First, it has heat resistance to heat generated during manufacturing, good workability for opening the through-hole hole 53, and high resistance to electrolytic plating, and further, an electrolytic metal plating layer is hardly formed on the mask surface. A mask material that can be satisfactorily removed in the step shown in (g) is preferable. For example, there is a mask material that is easy to close the opening and is laminated with an adhesive.

  The pressure-sensitive adhesive material is applied to the film-like first mask 31 and adheres the first mask 31 to the surface of the first conductor layer 21. The adhesive material has heat resistance to heat generated during production, good workability for opening the through-hole hole 53, and high resistance to electrolytic plating, and can be removed well in the step shown in FIG. 2 (g). The removal method in the step shown in FIG. 2 (g) is, for example, an adhesive material that can be easily peeled off by irradiating with ultraviolet rays or an adhesive material having a low adhesive force.

  In addition, a resin film is used for the first mask 31, and the removal of the first mask 31 at a position corresponding to the opening of the through-hole hole 53 is performed by opening the through-hole hole 53 on the second conductor layer 22 side. It is good to carry out by irradiating a laser beam. In this case, the position and shape of the through hole 53 and the opening of the first mask 31 corresponding to the opening can be accurately matched.

  Further, a photosensitive resin is used for the first mask 31, and the removal of the first mask 31 at a position corresponding to the opening of the through-hole hole 53 is performed by opening the through-hole hole 53 on the second conductor layer 22 side. When the exposure is performed from the part, the position and shape of the through hole 53 and the opening of the first mask 31 corresponding to the opening are matched exactly. Can do.

  At this time, the characteristics of the mask material include the performance of the mask (heat resistance to heat generated during manufacture, good workability for opening the through-hole hole 53, and high resistance to electrolytic plating treatment, It is preferable to use a water-soluble material that is less likely to form an electrolytic metal plating layer and can be removed well in the process shown in FIG.

  Next, the double-sided circuit board manufactured in the above-described Example 1 and Example 2 will be described with reference to FIG. 4 which is a sectional view thereof.

  As shown in FIG. 4, the double-sided circuit board includes a first conductor layer 21 formed on one surface of the insulating substrate 10 and a second conductor layer 22 formed on the other surface, and a through-hole hole 53 penetrating therethrough. Is formed. A first through hole plating 41 and a second through hole plating 42 are formed in the through hole hole 53, and the first conductor layer 21 and the second conductor layer 22 are electrically connected. ing. Further, after the series of manufacturing steps shown in FIG. 1 or FIG. 2, the first conductor layer 21 and the second conductor layer 22 are etched to form a conductor pattern on the insulating substrate 10. Is formed. Etching is performed by the following method. An etching resist is formed on the surface of the conductor layer 2, and the etching resist is patterned into an arbitrary shape by an exposure process and a development process using a photomask. Using this etching resist as a mask, the conductor layer 2 is etched to form a conductor pattern.

  The double-sided circuit board of the present invention thus obtained has a structure that is resistant to the thermal cycle applied to the insulating substrate 10 and is not easily disconnected because the through-hole plating 4 is not laminated stepwise on the through-hole land 52. ing.

  FIG. 5 is a cross-sectional view of a multilayer circuit board manufactured using the double-sided circuit board according to the present invention. In the multilayer circuit board shown in FIG. 5, two double-sided circuit boards 100 are laminated via an adhesive 61. The adhesive 61 is used to bond a plurality of double-sided circuit boards 100, and is used by being applied to the adhesive surface of the double-sided circuit board 100. As the adhesive 61, a thermosetting adhesive, a thermoplastic adhesive, an adhesive, or the like is used, and these may be used in combination.

  Here, in the double-sided circuit board 100 of the present invention, since the through-hole plating 4 is not laminated stepwise on the through-hole land 52 and the surface of the board is less uneven, the multilayer circuit board as shown in FIG. Even if it is formed, there is little possibility that voids are formed on the bonding surface, and the layers are difficult to peel off.

  Furthermore, since the inside of the through-hole hole 53 is completely filled with the through-hole plating 4 after the electrolytic metal plating process, the double-sided circuit board 100 of the present invention can be covered with a protective film, Even if the double-sided circuit board 100 is used to fabricate a multilayer circuit board as in 5, the closed space is not formed in the through-hole hole 53. Thereby, the problem of disconnection of the through-hole connection caused by thermal expansion of air in the closed space does not occur.

  FIG. 6 is a cross-sectional view of a build-up multilayer circuit board manufactured using the double-sided circuit board according to the present invention. The build-up multilayer circuit board shown in FIG. 6 includes an insulating layer 11 laminated on both surfaces of the double-sided circuit board 100, and a third conductor layer 23 laminated on the surface of these insulating layers 11. Electrical connection between the conductor layer 23 and the conductor layer 2 provided on the double-sided circuit board 100 is made through the through-hole connecting portion 51 and the via 45.

  The insulating layer 11 is laminated so as to electrically insulate the conductor layer 2 provided on the double-sided circuit board 100 and the third conductor layer 23 laminated on the surface of the insulating layer 11. Although it does not specifically limit as the insulating layer 11, Generally, the insulating layer which impregnated the epoxy resin to the glass cloth called a prepreg is used since intensity | strength and dimensional accuracy are favorable.

  The third conductor layer 23 is laminated on the outer surface of the insulating layer 11. The conductor layer 23 is not particularly limited as long as it is a conductive material.

  The via 45 is used to electrically connect different conductor layers through a hole called a via hole in the multilayer circuit board. The manufacturing method and material of the via 45 are not particularly limited and are generally formed by electroless plating or filling with a conductive substance.

  The through-hole connecting portion 51 is a portion composed of a through-hole land 52, a first through-hole plating 41, and a second through-hole plating 42. The through-hole land 52 is a conductor pattern formed by etching, and is a portion formed around the through-hole hole 53 for connecting the through-hole between the two conductor layers 2 provided on the insulating substrate 10. is there.

  Here, in the double-sided circuit board 100 of the present invention, the through-hole plating 4 is not laminated stepwise on the through-hole land 52, and the surface of the double-sided circuit board 100 has few irregularities. Even if it forms, there is little possibility that a space | gap will be formed in an adhesion surface, and it becomes difficult to peel between layers.

  Furthermore, since the inside of the through-hole hole 53 is completely filled with the through-hole plating 4 after the electrolytic metal plating process, the double-sided circuit board 100 of the present invention can be covered with a protective film, Even when the multilayer circuit board is manufactured using the double-sided circuit board 100 as in FIG. 6, the closed space is not formed in the through-hole hole 53. Thereby, the problem of disconnection of the through-hole connection caused by thermal expansion of air in the closed space does not occur.

  In the build-up multilayer circuit board shown in FIG. 6, the insulating layer 11 and the third conductor layer 23 are formed on each side of the double-sided circuit board 100. The double-sided circuit board 100 only needs to have at least one set of the insulating layer 11 and the third conductor layer 23 formed on one side or both sides thereof.

  FIG. 7 is a sectional view according to the double-sided circuit board of the present invention on which components are mounted. As shown in FIG. 7, a component 71 is mounted on the through-hole connection portion 51 of the double-sided circuit board 100 with solder 72. Since the double-sided circuit board 100 according to the present invention has less irregularities on the surface, when the component 71 is mounted on the surface of the board, the connection between the component 71 and the circuit of the double-sided circuit board 100 and the both sides of the component 71 are performed. Fixing to the circuit board 100 can be easily performed.

  FIG. 8 is a cross-sectional view of a double-sided circuit board according to the present invention on which connector terminals are mounted. As shown in FIG. 8, connector terminals 83 are mounted on the through-hole connecting portion 51 of the double-sided circuit board 100 according to the present invention. Since the double-sided circuit board 100 has less unevenness on the surface, the terminal 83 of this connector can be stably mounted on the through-hole connecting portion 51, and the connection of the terminal 83 of this connector is performed well.

  FIG. 9 is a cross-sectional view of a double-sided circuit board according to the present invention on which a slider fixed contact is mounted. As shown in FIG. 9, a fixed contact 92 for sliding the slider 91 is mounted on the through-hole connecting portion 51 of the double-sided circuit board 100 according to the present invention. Since the double-sided circuit board 100 has less irregularities on the surface, the fixed contact 92 can be stably mounted on the double-sided circuit board 100, and the slider 91 can be slidably contacted on the fixed contact 92.

It is sectional drawing of the double-sided circuit board which shows the manufacturing process in Example 1 of this invention. It is sectional drawing of the double-sided circuit board which shows the manufacturing process in Example 2 of this invention. It is sectional drawing of the double-sided circuit board which shows the growth state of through-hole plating formed by the electrolytic plating process of this invention. It is sectional drawing of the double-sided circuit board based on this invention. It is sectional drawing of the multilayer circuit board produced using the double-sided circuit board based on this invention. It is sectional drawing of the buildup multilayer circuit board produced using the double-sided circuit board based on this invention. It is sectional drawing of the double-sided circuit board based on this invention with which components were mounted. It is sectional drawing of the double-sided circuit board based on this invention with which the terminal of the connector was mounted. It is sectional drawing of the double-sided circuit board based on this invention with which the fixed contact of the slider was mounted. It is sectional drawing of the double-sided circuit board produced with the conventional manufacturing method. It is sectional drawing of the double-sided circuit board produced with the conventional manufacturing method.

Explanation of symbols

10 Insulating substrate
11 Insulating layer
2 Conductor layer
21 First conductor layer
22 Second conductor layer
23 Third conductor layer
31 First mask
32 Second mask
4 Through-hole plating
41 First through hole plating
42 Second through hole plating
43 Electrolytic metal plating layer
44 Laminate
45 Via
51 Through-hole connection
52 Through Hole Land
53 Through-hole hole
61 Adhesive
71 parts
72 Solder
81 coating
82 Reinforcing plate
83 Connector terminals
91 Slider
92 Fixed contact
100 Double-sided circuit board

Claims (12)

In the method for manufacturing a double-sided circuit board in which the conductor layers provided on both sides of the insulating substrate are electrically connected via through-holes,
Forming a conductor layer on each side of the insulating substrate;
A step of forming a first mask on the surface of the first conductor layer, with one of these conductor layers being a first conductor layer and the other being a second conductor layer;
Forming a through-hole hole penetrating the first mask, the first conductor layer, the insulating substrate, and the second conductor layer;
Forming a second mask on the surface of the second conductor layer so as to close the opening on the second conductor layer side of the through-hole hole;
A first through-hole plating is formed in the through-hole hole by energizing the first conductive layer, and a second through-hole plating is formed in the through-hole hole by energizing the second conductive layer. Forming, and
A method for manufacturing a double-sided circuit board, comprising: removing the first mask and the second mask. In the method for manufacturing a double-sided circuit board in which the conductor layers provided on both sides of the insulating substrate are electrically connected via through-holes,
Forming a conductor layer on each side of the insulating substrate;
One of these conductor layers is used as a first conductor layer, and the other is used as a second conductor layer, and a through-hole is formed through the first conductor layer, the insulating substrate, and the second conductor layer. And a process of
A first mask is formed on the surface of the first conductor layer so as to close the opening on the first conductor layer side of the through-hole hole, and the first portion of the portion corresponding to the opening is formed. Removing the mask of 1;
Forming a second mask on the surface of the second conductor layer so as to close the opening on the second conductor layer side of the through-hole hole;
A first through-hole plating is formed in the through-hole hole by energizing the first conductive layer, and a second through-hole plating is formed in the through-hole hole by energizing the second conductive layer. Forming, and
A method for manufacturing a double-sided circuit board, comprising: removing the first mask and the second mask.   The method for manufacturing a double-sided circuit board according to claim 1, wherein a resin film is used for the first mask.   A resin film is used for the first mask, and the removal of the first mask at a position corresponding to the opening of the through-hole hole is performed by laser from the opening of the through-hole hole on the second conductor layer side. The method for producing a double-sided circuit board according to claim 2, wherein the method is performed by irradiating light.   A photosensitive resin is used for the first mask, and the removal of the first mask at a position corresponding to the opening of the through-hole hole is performed from the opening of the through-hole hole on the second conductor layer side. The method for producing a double-sided circuit board according to claim 2, wherein the method is performed by exposure.   6. The double-sided circuit board according to claim 1, wherein the second mask is provided on the second conductor layer through an adhesive material mixed with particles of a conductive material. Manufacturing method.   The method for manufacturing a double-sided circuit board according to claim 6, wherein the particles of the conductive material are non-metallic.   The method for manufacturing a double-sided circuit board according to claim 7, wherein the particles of the conductive material are carbon particles.   9. The method for manufacturing a double-sided circuit board according to claim 8, wherein the particles of the conductive material are carbon nanotube particles.   The method for manufacturing a double-sided circuit board according to any one of claims 1 to 9, wherein the second through-hole plating is formed before the first through-hole plating.   The method for manufacturing a double-sided circuit board according to any one of claims 1 to 10, wherein the first and second through-hole plating is performed using a copper-based plating material.   A double-sided circuit board manufactured by the manufacturing method according to claim 1.

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